Route Services

This documentation is intended for service authors who are interested in
offering a service to a Cloud Foundry (CF) services marketplace. Developers
interested in consuming these services can read the Manage Application Requests with Route Services topic.

Introduction

Cloud Foundry application developers may wish to apply transformation or
processing to requests before they reach an application. Common examples of use
cases include authentication, rate limiting, and caching services. Route
Services are a kind of Marketplace Service that developers can use to apply
various transformations to application requests by binding an application’s
route to a service instance. Through integrations with service brokers and,
optionally, with the Cloud Foundry routing tier, providers can offer these
services to developers with a familiar, automated, self-service, and on-demand
user experience.

Note: The procedures in this topic use the Cloud Foundry Command Line Interface (cf CLI). You can also manage route services using Apps Manager. For more information, see the Manage Route Services section of the Managing Apps and Service Instances Using Apps Manager topic.

Architecture

In each model, you configure a route service to process traffic addressed to an
app.

Fully-Brokered Service

In the fully-Brokered Service model, the CF router receives all traffic to apps
in the deployment before any processing by the route service. Developers can
bind a route service to any app, and if an app is bound to a route service, the
CF router sends its traffic to the service. After the route service processes
requests, it sends them back to the load balancer in front of the CF router.
The second time through, the CF router recognizes that the route service has
already handled them, and forwards them directly to app instances.

The route service can run inside or outside of CF, so long as it fulfills the
Service Instance Responsibilities to
integrate it with the CF router. A service broker publishes the route service
to the CF marketplace, making it available to developers. Developers can then
create an instance of the service and bind it to their apps with the following
commands:

Traffic to apps that do not use the service makes fewer network hops because requests for those apps do not pass through the route service.

Disadvantages:

Traffic to apps that use the route service makes additional network hops, as compared to the static model.

Static, Brokered Service

In the static, brokered service model, an operator installs a static routing
service, which might be a piece of hardware, in front of the load balancer. The
routing service runs outside of Cloud Foundry and receives traffic to all apps
running in the CF deployment. The service provider creates a service broker to
publish the service to the CF marketplace. As with a fully-brokered service, a developer can use the service by instantiating it
with cf create-service and binding it to an app with cf bind-route-service.

In this model, you configure route services on an app-by-app basis. When you
bind a service to an app, the service broker directs the routing service to
process that app’s traffic rather than pass the requests through unchanged.

Advantages:

Developers can use a Service Broker to dynamically configure how the route service processes traffic to specific applications.

Traffic to apps that use the route service takes fewer network hops.

Disadvantages:

Adding route services requires manual infrastructure configuration.

Traffic to apps that do not use the route service make unnecessary network hops. Requests for all apps hosted by the deployment pass through the route service component.

User-Provided Service

If a route service is not listed in the CF marketplace by a broker, a developer
can still bind it to their app as a user-provided service. The service can run
anywhere, either inside or outside of CF, but it must fulfill the integration
requirements described in Service Instance Responsibilities. The service also needs
to be reachable by an outbound connection from the CF router.

This model is identical to the fully-brokered service model,
except without the broker. Developers configure the service manually, outside
of Cloud Foundry. They can then create a user-provided service instance and bind it to their application with the following commands, supplying the URL of their route service:

Enabling Route Services in Pivotal Cloud Foundry

You configure Route Services for your deployment in the PAS tile, under Settings > Networking. Depending on your infrastructure, refer to the PAS configuration topics for AWS, OpenStack, or vSphere.

Service Instance Responsibilities

The following applies only when a broker returns route_service_url in the bind response.

How It Works

Binding a service instance to a route associates the route_service_url with the route in the CF router. All requests for the route are proxied to the URL specified by route_service_url.

Once a route service completes its function it may choose to forward the request to the originally requested URL or to another location, or it may choose to reject the request; rejected requests will be returned to the originating requestor. The CF router includes a header that provides the originally requested URL, as well as two headers that are used by the router itself to validate the request sent by the route service. These headers are described below in Headers.

Headers

The following HTTP headers are added by the Gorouter to requests forwarded to route services.

X-CF-Forwarded-Url

The X-CF-Forwarded-Url header contains the originally requested URL. The route service may choose to forward the request to this URL or to another.

X-CF-Proxy-Signature

The X-CF-Proxy-Signature header contains an encypted value which only the Gorouter can decrypt.

The header contains the originally requested URL and a timestamp. When this header is present, the Gorouter will reject the request if the requested URL does not match that in the header, or if a timeout has expired.

X-CF-Proxy-Signature also signals to the Gorouter that a request has transited a route service. If this header is present, the Gorouter will not forward the request to a route service, preventing recursive loops. For this reason, route services should not strip off the X-CF-Proxy-Signature and X-CF-Proxy-Metadata headers.

If the route service forwards the request to a URL different from the originally requested one, and the URL resolves to a route for an application on Cloud Foundry, the route must not have a bound route service or the request will be rejected, as the requested URL will not match the one in the X-CF-Proxy-Signature header.

X-CF-Proxy-Metadata

The X-CF-Proxy-Metadata header aids in the encryption and description of X-CF-Proxy-Signature.

SSL Certificates

When Cloud Foundry is deployed in a development environment, certificates hosted by the load balancer are self-signed, and not signed by a trusted certificate authority. When the route service finishes processing an inbound request and makes a call to the value of X-CF-Forwarded-Url, be prepared to accept the self-signed certificate when integrating with a non-production deployment of Cloud Foundry.

Timeouts

Route services must forward the request to the application route within 60 seconds.

In addition, all requests must respond in 900 seconds.

Broker Responsibilities

Catalog Endpoint

Brokers must include requires: ["route_forwarding"] for a service in the catalog endpoint. If this is not present, Cloud Foundry will not permit users to bind an instance of the service to a route.

Binding Endpoint

When users bind a route to a service instance, Cloud Foundry sends a bind request to the broker, including the route address with bind_resource.route. A route is an address used by clients to reach apps mapped to the route. The broker may return route_service_url, containing a URL where Cloud Foundry should proxy requests for the route. This URL must have an https scheme, otherwise the Cloud Controller rejects the binding. route_service_url is optional, and not returning this field enables a broker to dynamically configure a network component already in the request path for the route, requiring no change in the CF router.

Example Route Services

Logging Route Service: This route service can be pushed as an app to Cloud Foundry. It fulfills the service instance responsibilities above and logs requests received and sent. It can be used to see the route service integration in action by tailing its logs.

Rate Limiting Route Service: This example route service is a simple Cloud Foundry app that provides rate limiting to control the rate of traffic to an application.

Tutorial

The following instructions show how to use the Logging Route Service described in Example Route Services to verify that when a route service is bound to a route, requests for that route are proxied to the route service.

Push a sample app like Spring Music. By default this creates a route spring-music.cf.example.com.

$ cf push spring-music

Bind the user-provided service instance to the route of your sample app. The bind-route-service command takes a route and a service instance; the route is specified in the following example by domain cf.example.com and hostname spring-music.